1. Field of the Invention
This invention relates to a document reader, and more particularly to a document reader which, when any region of a given manuscript is desired to be exclusively read out or copied, enables designation of the aforementioned region for reading or copying to be easily effected while the manuscript is left standing on a platen glass or kept inserted in a manuscript slot of the document reader.
2. Description of the Prior Art
The conventional electrophotographic copying machine is based on the principle that a copy of a given manuscript is obtained by illuminating the manuscript with a light from a light source and causing the light reflected on the surface of the manuscript to impinge directly on the surface of a photosensitive body thereby generating an electrostatic latent image on the photosensitive body.
In accordance with this method, the process for formation of the electrostatic latent image on the photosensitive body is wholly carried out under mechanical control. When the ratio of magnification used in copying the manuscript in an enlarged or reduced size is to be set at any desired value, therefore, mechanisms such as for adjustment of the lens position and for control of scanner speed greatly gain in complexity so much as to boost the cost of production of the electrophotographic copying machine. Besides, the desire to copy the manuscript exactly at a desired ratio of magnification proves difficult.
In consequence of the advance of various office automation machines, the conventional process of reading a given manuscript in a predetermined paper size such as A3 or A4 and producing the output on recording papers is no longer able to meet all the needs of the day. There have arisen needs which make it necessary to have only a pertinent region of a given manuscript exclusively read out and copied, or even to have only the pertinent region of the manuscript copied as enlarged or reduced at a desired ratio of magnification and/or rotated at a desired angle in a desired position on a recording paper (hereinafter the processing described above will be collectively referred to as "editing").
By the aforementioned method for formation of an electrostatic latent image under mechanical control, however, it is totally infeasible to confer the aforementioned editing function upon the electrophotographic copying machine.
In the circumstance, efforts are being devoted to the development of an electrophotographic copying machine which produces a copy of a given manuscript by illuminating the manuscript with a light from a light source, causing the light reflected on the surface of the manuscript to be read and converted into digital signals by a photoelectric element such as CCD, subjecting the digital signals to a proper processing, and thereafter forming an electrostatic latent image on the surface of a photosensitive body by the use of a light emitting element such as LED (hereinafter referred to as a digital copying machine).
One version of the aforementioned digital copying machine is disclosed in the specification of Japanese Patent Laid-open SHO No. 59(1984)-63,868. This specific digital copying machine is depicted in the specification as comprising a document reading device (reader) and a digital document reproducing device (printer).
When only a pertinent region of a given manuscript is to be read out by the document reading device disclosed in the aforementioned specification, the following operation must be carried out.
The operator, before placing the manuscript on a platen glass, is required to cover the manuscript with a transparent sheet having checkers printed thereon for reading coordinates in such a manner that the reference line on the manuscript will coincide with that on the checkers, read the coordinates of the pertinent region of the manuscript (or the masking region of the manuscript), and then feed in the numerical values of the coordinates through a ten-key arranged on the operation panel for the document reading device.
FIG. 2 is a schematic diagram for illustrating the correspondence between the face of the manuscript and the regions on the document recording memory. FIG. 2(a) represents the face of the manuscript and FIG. 2(b) the document recording memory.
When only a region indicated by hatch lines in the entire face of the manuscript shown in FIG. 2(a) is desired to be read or to be masked, the transparent sheet having checkers printed thereon is placed as described above to cover the manuscript.
Then, the distances x.sub.O and x.sub.O +.DELTA.x in the direction of main scanning (the direction indicated by the arrow x) from the reference line L.sub.y and the distances y.sub.O and y.sub.O +.DELTA.y in the direction of sub-scanning (the direction indicated by the arrow y) from the reference line Lx are read out. The numerical values of these distances are fed in through the ten-key.
Between the numerical values fed in through the ten-key as described above and a region of the document data memory (defined by the coordinates of the directions indicated by the arrows X and Y) illustrated in FIG. 2 (b), the following known functional relations exist, for example.
f(x)=X PA1 f(y)=Y PA1 (1) If the numerical values of the coordinates of the pertinent region of the manuscript are read out erroneously or they are fed in erroneously through the ten-key, the portion of the manuscript actually read out or the copy of the manuscript formed on the recording paper may deviate from the region desired to be copied. Thus, the produced copy is found to be rejected. PA1 (2) Even if the numerical values of the coordinates of the pertinent region of the manuscript are correctly read out and then are fed in correctly through the ten-key, there is still the possibility that a reference line of the manuscript will deviate from a reference line of the checkers printed on the transparent sheet or the manuscript will not be correctly placed at the prescribed position on the platen glass. This incorrect location of the manuscript results in production of a rejectable copy. PA1 (3) When a pertinent region is selected in the manuscript, the manuscript is placed so that the face of the manuscript will fall on the upper side. When the manuscript is exposed to light for copying, the manuscript is placed on the platen glass in such a manner that the face of the manuscript will fall on the lower side. Thus, the handling of the manuscript during the copying work takes up twice as much time and labor as the handling involved in the case of the ordinary electrophotographic copying machine. The operator tending the document reading deivce, therefore, is burdened with a highly troublesome job. PA1 (4) The setting of the pertinent region of the manuscript has no alternative but to rely on the procedure of actually measuring the pertinent region and subsequently feeding in the numerical outcomes of the measurement through the ten-key. This particular procedure proves to be a toublesome job for the operator.
The region indicated by hatch lines in FIG. 2(b), therefore, can be set on the document data memory by allowing the numerical values, x.sub.O, x.sub.O +.DELTA.x, y.sub.O, and y.sub.O +.DELTA.y, fed in by the operation of the ten-key to be processed as by a micro-computer. In other words, the numerical values of X.sub.O, X.sub.O +.DELTA.X, Y.sub.O, and Y.sub.O +.DELTA.Y can be set and, as the result, only the pertinent region of the manuscript can be read out.
In FIG. 2, the pertinent region of the manuscript desired to be read out is depicted as a rectangle having four sides parallel to the direction of main scanning or sub-scanning. Optionally, the pertinent region may be a polygon so long as all the sides of the polygon run parallelly to the direction of main scanning or the direction of sub-scanning.
In the foregoing description, the document data are presumed to be tentatively stored in the memory. Instead of elaborately assigning the memory to the tentative storage of the data, the signals representing the information in the pertinent region of the face of the manuscript can be fed out on the real-time basis (optionally after being subjected to a proper processing).
In accordance with the conventional method described above, when only a pertinent portion of a given manuscript is desired to be read out, the operator is required, before placing the manuscript on a platen glass, to cover the manuscript with a transparent sheet having checkers printed thereon for reading coordinates, read out the numerical values of the coordinates of the pertinent region of the manuscript with reference to the checkers on the transparent sheet, and feed in the numerical values through the ten-key arranged on the operation panel for the document reading device as already described above. Thus, the conventional method has entailed the following disadvantages.